Process and apparatus for drawing sheet glass



H. P9X ET AL.

Sept. '7 9 51925.,

PROCESS AND APPARATUS FOR DRAWING SHEET GLASS 4 Sheets-Sheet 1 Filed Jan. 13 1926 iNVENTOR AW/Z 2 Sepm 5' F226. 1,598,765

.1. H FOX ET AL PROCESS AND APPARATUS FOR DRAWING SHEET GLASS Filed Jan. 13, 1926 4 Sheets-Sheet I5 INVENTORJ Sept. 2' 2926.

J. H. FOX ET AL PROCESS AND APPARATUS FOR DRAWING SHEET GLASS Filed Jan. 13. 1926 4 sheats slleet 4 INVENTOR 5 draw occurs. it.

* ute'ited ent. "i, i iih iiiii WWI-mm. gnmmmn d'tilihi' FOX. AND HARRY F. EITHER, O]? PITTEiBUlEt EiH, runner .f-

rnootss AND iiIEPA..MTUi

Application filed .Touuary The invention relates to o poratus for drawing sheet glass, and particularly to the heating or reconditioning of the portion of the bath from WillCh the draW-heroi clay is often employed in the bath underneath the line of generation oi e. gloss sheet and in the course of time, s certain amount of deprocess and apvitrification occurs upon the upper side of in the her, so that the operation must be stopped. from time to time, the drawing opening covered over end the surface glass suhject to a reheating operation tor one or.

more hours before the draw is continued The purpose oi the invention is to reduce this ices oi by the use of on electricui g errangeinent. which. can be out into onerution ironi time to time and "which Wlii secure reheating and reconditioning 0'1": the glass in a relatively short period of time. The invention is also oi use even Where no drew-bar is employed in the bath, as even without a draw-hair it becomes desirable to reheat the surface glass in the bath from time to time. The process is further not limited to an intermittentoperation, as the electric heating means may be employed, either when adruvv-har' is used or when it is not used, to keep the surface glass from which the sheet is generated at a uniform temperature during the drawing operation. The temperature condition may be adjusted by this means to any desired degree by merely regulating the flow of electric current. Certain embodiments of the invention are illustrated. in the accompanying drawings, wherein:

Figure -1 is a vertical section on the line i-li of Fig. 2. Fig. 2 is a section on the iine H-H of Fig. 1. Fig 3 isa partial horizontal section on the line III-411' 01 Fig. 1. Fig. 4% is Fig. 3, but showing o modified iorni of floater. And Figs. 5, 6 and 2' are views similar to those of Figs. 1, 2 and 3, but showing.

a further modification.

Referring to Fig. 1, the numeral 1 ignotes the end of a having an extension or fiireheerth 2 pairtielly cut. oil from the tank'hy means of the gate 3 and provided with 9. cover ortop in the form of the plates i and 5 and.t11e L blocks 6 and 7, between which is the drawiug opening. The glass sheet 8 is drawn up dos 5 section similar to that of ore supplied with glass melting tank or new.

3.3, 19%. No. sense.

il end. 12 are the surface oi hloehs end the sheet pair of holding devices 3123., 13, such those illustrated and descriheri. Siingiufi Patent No. Liidhfiifi; oi ii The means for pulling the upward from. the hath. cooling it after it ieeves the bath, and holding its edges against inward movement constitute no invention which relates entirely to the prod ess and apperatus for conditioning" the glass in the bath and maintaining it at it proper temperature as hereinafter described.

Extending longitudinally of the line of generation of the sheet 8., end spaced he neath the surface of the glass, is a 'di'avvhar 14 of refractory material, such as clay 'such draw-bur assisting in cooling the layer of glass thereabove from which the sheet is drawn and serving to maintain the line of generation of the sheet constant during thev drawing operation.

draw-bar is a floater material, such us ciay,'which floaters act'as skimming devices and. purities from being drawn into the sheet. Each of these bars is provided along its front side heiovv the surface of the glass with uftrough or groove 16, and these troughs are iiiied with molten metal, such as antimony, suitable for form ing an electrode and oi a. character such that the glass will not .reacttherewith and uroduce discoloration. These troughs of nietel flow of electric current through the terminals 1? and 18. having Q11 each side of the their ends extended down into the molten metal. 'These terminals should be of a coin position suitable forresisting high te1nper- 'atures and not readily acted upon by the molten glass. Two of such-compositions are the well-known niehroine and askalov. Electric current is supplied from; a suituhle generator. The floaters 15, it; are preterably bowed. swey iroin. eeoiiother as in 9 which. is "provided with part of the present 15, also of refractory 7 prevent surface he. carried along and dicated in Fig. 3 for a purpose as herein after set forth, although such floaters may be parallel, as indicated in Fig. 4.

If, during the course of the draw, devitri- ;ficd glass is formed above the draw-bar l t,

yitrification are removed. Ordinarily, the

drawing of the sheet 8 will be discontinued during this reinelting operation, although this is not necessarily the case. This re heating may be accomplished withoutre moving the water coolers it and 12 or the edge holding members 13, although it is desir-able to remove the latter in case the draw .is discontinued during the remelting operation. It is not necessary to cover over the drawing opening between the L-blocks during the reheating operation, so that there is-no requirement for removing the water coolers 11 and 12 and the reheating operation may be carried out much more rapidly and with less inconvenience than occurs with the present method of reconditioning the glass which calls for the removal of the water coolers and the placing of a cover plate over the drawing opening between the L-blocl s.

The invention may be also employed for regulating the temperature of the glass during the drawing operation and this also aphes when no draw-bar is employed. Un-

er these conditions, the flow of current is, of course, much less than that employed if remelting or reheating in order to remove devit iiied glass, only enough current being supplied to keep the surface glass at exactly the right temperature for securing the desired results in the drawing of the sheet. Under this condition of continuous operation, it is desirable to have the floaters 15, 15 bowed, as indicated in Fig. 3, in order that the heating ell'ect of the current will be less at the center of the sheet than at the edges, since the temperature of the glass bath in a tank is normally higher adjacent the center than at the edges and a tendency always exists to draw the sheet thinner at the center than at the edges. The bowed skimming bars with their electrodes compensate for this condition, which, however, is not an essential as other expedients may be adopted for re ulatin the torn )erature of the bath from which the sheet is drawn, so that the central portion. of the bath is given a temperature treatment reducing the ten'iperature of this portion of the hath as compared with that at the edges of the tank.

wearers In the construction, as shown in Fig. 4, the floaters 15, 15 are straight and parallel to each other instead of being bowed, the construction in other respects being the same as that of Figs. 1, 2 and 3' and similar reference numerals being used throughout In the construction shown in Figs. 5, 6 and 7, the electrodes 15, 15 of Fig. l are dispensed with and the heating current above the draw bar 19 is directed crosswise of the tank between the electrodes :20 and 21 which are of molten metal lying in iockets or troughs in the side walls 22, 22 a jacent the surface ofthe glass Iurrent is supplied to the electrodes from the terminals 23 and 24, thus causing a. flow of current through the layer of lass above the draw-bar 19 and longitudinally of such bar instead of transverscly, as is the case in the Fig. 1 construction. .The purpose here is to provide for the reinelting from time to time of any devitrified glass which may be formed upon the upper surface of the draw-bar 19. The other parts of the construction are similar to those of the Fig. lconstruction and are similarly designated by reference numbers.

What we claim is:

1. A process of drawing glass, which consistsin drawing a sheet upwardly from a molten bath, and passing a flow of electric current through the bath so that the major portion thereof flows through the layer of glass at the surface of the bath from which the sheet is drawn.

2. A process of drawing glass, which consists in drawing a-sheet upwardly from a molten bath, and, from time to time, passing a flow of electric current through the layer of lass at the surface of the bath from whic the sheet is drawn so as to heat such glass above the normal drawing tempcrature .in order to rccondition the glass.

3. A process of drawing glass, which consists in drawing a sheet upwardly from a molten bath, segregating the layer of glass at the surface of the bath from which the sheet is generated, from the main body of glass ther beneath, and heating such layer of glass by passing a current of electricity thercthrough.

4. A process of drawing glass, which consists in drawing a sheet upwardly from a molten hath, segregating the layer of glass at the surface of the bath from which the sheet is generated, from the main body of glass therebeneath, and reheating such layor of glass at intervals by passing a current of electricity therethrough.

5. A process of drawing glass, which con sists in drawinga sheet upwardly from a. molten oath, segregating the layer of glass at the surface of the bath fronrwhich the sheet is generated, from the main. body of glass thereheneatl and seating such layer I of glass by passing a current of electricity therethrough in a direction transverse to the line of generation of the sheet.

6. A process of drawing glass, which consists in drawing a sheet upwardly from .a molten bath, and passing a flow of electric current through the bath so that the major portion thereotflows through the layer'of glass at the surface of the bath from which the sheet is drawn, the said flow of current being in a direction transverse to the line of generation of the sheet.

7. A process of drawing glass, which consists in drawing a sheet upwardly from a molten bath, and passing a flow of electric current through the bath so that the major portion thereof flows through the layer of glass at the surface of the bath from which the sheet is drawn, the said flow of currentbeing in a direction transverse to the line of generation ofthe sheet, and in an amount decreasing from the edges of the sheet to the center, so that the glass bath is heated to a less degree at the center of the sheet than at the edges.

8. The combination with a glass tank, and means for drawing a sheet continuously therefrom, of an electrode at each side of the line of generation of the sheet adjacent the surface of the glass, and means for causing a flow of electric current through the layer of glass therebetween from which the sheet is drawn.

9. The combination with a glass tank, and means for drawing a sheet COI tinnously therefrom, of an electrode at each side of the line of generation of the sheet adjacent the surface of the glass, and means for causing a flow of electric current through the layer of glass therebetween from which the sheet is drawn, said electrodes being bowed away from each other at theircenters.

10. The combination with a glass tank, and means for drawing a sheet continuously therefrom, of a draw-baro1t refractory material extending transversely of the tank and submerged below the surface of the glass, and means for passing a current of electricity through the layer of glass lying above such bar.

11. The combination with a glass tank, and means for drawin a sheet continuously therefrom, of a drawer of refractory ma terial extending transversely of the vtank and submergedbelow the surfaceof the glass, an electrode at each side of the draw bar adjacent the surface of the glass, and

means for causing a flow of electric current through the layer of glass above the bar from one electrode to the other.

12., The combination with a glass tank,

and means for drawing a sheet continuously therefrom, of a draw-bar of refractory material extending transversely of the tank and submerged below the surface of the glass, electrodes of molten metal in opposition to each other adjacent the level of the glass bath, and means for causing a current of electricity to flow therebetween through the layer of glass lyingabove the drawdaar.

18. The combination with a glass tanlr, and means for drawing a sheet continuously therefrom, of a drawbar of refractory ma terial extending transversely of the tank and submerged below the surface of the glass, electrodes of molten metal on opposite sides of the draw-bar in contact with the upper portion of the molten glass, and means for causing a current of electricity to flow there-- between through the layer of lying above the draw-bar.

i i. The combination with a glass tank, and means for drasvins, a sheet continuously therefrom.- ot a draw-bar of refractory into terial. extending transversely of the tunic and. submerged below the surface of the glass, electrodes of molten metal on opposite sides of the draw-bar in contact with the any portion of the molten glass and eutendi longitudinally of the draw-bar, and means for passing a current of electricity through the layer of glass lying above such bar.

15. The combination with a glass tent; and means for drawing a sheet continuously therefrom, of a, draw-bar of'refraetory material extending transversely or'the tank and submerged below the surface of the glass, clay members also extending transversely of the tanlr on each side of the i'liu'nvbar, each provided on its side toward the draw-bar and at the level of the bath with iongitur i nal trough or pocket, electrodes in. the for i of molten metal lying in said troughs in contact with the molten glass, and means for passing a current of electricity between the electrodes and through the layer of glass above the draw-bar.

16. The combination with a glass tanlr, and means for drawing a sheet continuously therefrom clay members extending transversely of the tank on opposite sides of the line of draw of the sheet and each provided on its side toward the drawbar and. the.

m m Oil llltl 

